For example, as shown in FIG. 5, a displacement control valve 50 for controlling the discharge rate of a variable displacement compressor according to pressure loads includes a valve housing 51 formed with a metal material or a resin material, a valve element 52 disposed reciprocably in the valve housing 51, a pressure-sensitive element 53 biasing the valve element 52 in one direction, a solenoid 54 connected to the valve housing 51, for exerting an electromagnetic driving force on the valve element 52, and others.
The solenoid 54 includes a casing 55 coupled to the valve housing 51, an end member 56 provided in such a manner as to seal an upper opening of the casing 55, a sleeve 57 closed at one end, a cylindrical fixed iron core 58 disposed inside of the casing 55 and the sleeve 57, a driving rod 59 coupled to the valve element 52 at its distal end reciprocably in the inside of the fixed iron core 58, a movable iron core 60 fixed to the other end of the driving rod 59, a coil spring 61 biasing the movable iron core 60, an exciting coil 62 wound on the outside of the sleeve 57 via a bobbin, and others. The casing 55 and the end member 56 are integrally joined together by caulking an upper end of the casing 55. An O-ring 78 is provided between them to seal the interior of the solenoid 54.
The valve housing 51 includes a first valve chest 65 formed in the middle of a discharge-side passage, a second valve chest 66 formed in the middle of a suction-side passage, a third valve chest 67 formed close to a control chamber (not shown) of the variable displacement compressor, and others.
Ps represents suction pressure, Pd discharge pressure, and Pc control chamber pressure.
The displacement control valve 50 like this is inserted into a mounting hole 71 formed in a casing 70 of the variable displacement compressor, and is fixed by attaching a C-ring 74 to an opening end of the mounting hole 71. In that state, ports 65a, 66a, and 67a of the first valve chest 65, the second valve chest 66, and the third valve chest 67 communicate with refrigerant passages in the casing 70. To seal the ports 65a, 66a, and 67a, a first O-ring 68 and a second O-ring 69 are fitted in recessed portions of the valve housing 51, and a third O-ring 72 is fitted in a recessed portion of the casing 55. A fourth O-ring 73 is provided at a joint between the casing 55 and the end member 56 and on the outer periphery of an upper end portion of the casing 55. Contact between the O-ring 73 and an inner peripheral surface of the mounting hole 71 prevents the inflow of water, mud, and the like from the outside (see an arrow 75), which is a known invention (Hereinafter, it is referred to as “Conventional Art 1”. See Patent Document 1, for example.).
There is also a known invention in which, in place of the fourth O-ring 73 in Conventional Art 1, an elastically deformable lip-shaped sealing member is provided by integral molding to the outer peripheral side of the end member 56 in such a manner as to face the opening end of the mounting hole 71 (Hereinafter, it is referred to as “Conventional Art 2”. See Patent Document 2, for example.).